Transformer



Patented Apr. 9, 1929.

UNITED ySTATES-PATENT OFFICE.

WILLIAM E. PAUL, F SCHENCTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

TRANSFORMER.

Application led May 18,

My invention relates to-transformers.v A transformer usually includes amagnetic core and primary and secondary windings. Current in the primary windin g induces magnetic vflux in the core and this flux induces inthe secondary windinol a voltage which will cause a current to flow if asuitable path is provided between the secondary terminals. Itissometimes desirable to limit the secondary current to some definitemaximum value even when the values of the voltage and current in theprimary winding are greater than necessary to produce this maximumsecondary current. This result has been obtained to some degree byarranging the core to become saturated by the amount of flux necessaryto produce the maximum secondary voltage and current. Any furtherincrease in primary voltage and current will then produce y only leakageflux and the amount of this leakage flux will not be very great becausethe reluctance of the leakage Hux path is high. The

amount of this leakage flux, however, may be very appreciable and thegeneral object of the invention is to provide an improved transformer ofthe saturated core type so arranged and constructed that the primaryleakage flux will not substantially affect the secondary voltage andcurrent.

rI'he invention will be better understood from the following descriptiontaken in connection with the accompanying drawing in which Fig. 1 is aperspective View of a transformer constructed in accordance with theinvention, and Figs. 2 and 3 are explanatory views of the transformershown in Fig. 1 with the windings shown in section.

-Like reference characters indicate similar parts in the differentfigures of the drawing. l In the particular construction shown in thedrawing, the transformer includes a laminated magnetic core 10 having a.central leg 11 and two outer legs 12 connected at their ends by yokes.The central leg 11 is surrounded by a winding 13. Each outer leg 12 hastwo end sections 14 connected to an offset intermediate section 15 byshort connecting sections 16 disposed at right angles to the central leg11 and to the axis of thewinding 13. There are thus four of theseconnecting core sections 16. Windings 17v surround respectively the fourconnecting core sections 16. These windings '17 may be connected in anydesired series or parallel or series-parallel 1928. Serial No. 278,844.

combination so that together they form a second wind-ing of thetransformer.

The main magnetic flux fiowing through Vthe core is indicated bythearrows in Figs. 2 and 3 and will be substantially the same whichever ofthe two windings 13 and 17 is used as the primary. When the number ofampere turns in the primary winding is greater than that necessary tosaturate the core, a leakage flux field will appear and this field willbe different depending upon which of the two windings 13 andV 17 is usedas the primary. ]f the winding 13 on the central core leg 11 is theprimary, the leakage fiux field 18V` indicated by broken lines in Fig. 2will,` be produced. If the windings 17 on the outer core legs areconnected to form the primary, leakage flux 19 as indicated by brokenlines in Fig. 3 will be produced.

In the arrangement which has been described, the windings 17 aredisposed beside the winding 13 and with their axes at right angles tothe axis of this winding 13. The windings 17 are thus disposed in theleakage magnetic field 18 which may be produced when the winding 13 isused as the primary and the axes of the windings 17 are at right anglesto the lines of force in the field 18. The voltages and currents in thewindings 17 are therefore not affected by this magnetic field or by anyincrease in ampere turns in the primary winding 13 after the core issaturated. 1n some cases, it may be found desirable to extend thecentral core leg beyond the end yokes as shown in Figs. 2 and 3 t0direct the lilies of force inthe magnetic held 18 more nearly at rightangles to the axes of the windings 17 at all points within thesewindings.

The leakage magneticfields 19 shown in Fig. 3 are produced when thewindings 17 are used as primary. If these fields reach the winding 13which is now` the secondary, their axes will be at right angles to theaxis of this secondary winding and the voltage and current in thesecondary winding will therefore not be affected and cannot increase inresponse to any increase in ampere turns in the windings 17 after thecore is saturated.

The invention has been explained by describing a specific form thereofbut it will be apparent that various changes may be made withoutdeparting from the scope of the invention as defined in the appendedclaims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A transformer including a magnetic core having a plurality of legs, awinding surroundingV one of said legs, a second leg having an endsection and a section oil'set from its end section, and a second Windingsurrounding said second leg between its end and its ofset sections, theaxes of said two windings being at substantially right angles to eachother.

2. A transformer including a magnetic core having a plurality of legs, awinding surrounding one of said legs, a second leg having two endsections and an mtermedlate section offset from its end sections, andwindings surrounding said second leg between its end and intermediatesections, the axes of the windings on said second leg being atsubstantially right angles to the axis of the other winding.

3. A. transformer including a magnetic core having a central leg and twoouter legs, a winding surrounding said central leg, each outer leghaving two end sections and an intermediate section oiset from its endsections, and windings surrounding each outerleg between its end andintermediate sections, the axes of the windings on said outer legs beingat substantially right angles to the axis of the winding on said centralleg.

In witness whereof, I have hereunto set my hand this 17th day oi May,1928.

WILLIAM E. PAUL.

